Motor operated compressor

ABSTRACT

A motor operated compressor according to the present invention has a driving motor having a stator and a rotor. A rotation shaft of the motor is coupled to the rotor. The compressor also has a frame, a fixed scroll positioned on one side of the frame, and an orbiting scroll supported on the frame and positioned between the fixed scroll and the frame. The fixed scroll forms a compression chamber together with the orbiting scroll. The driving motor, the fixed scroll, the orbiting scroll, and the frame are positioned within a casing of the compressor. The rotation shaft rotatably passes through the fixed scroll and the frame and is to eccentrically coupled to the orbiting scroll, allowing the orbiting scroll to perform an orbiting motion relative to the fixed scroll. One end portion of the rotation shaft is supported by the fixed scroll while the other end is supported by the casing.

CROSS-REFERENCE TO RELATED APPLICATION

Pursuant to 35U.S.C. § 119(a), this application claims the benefit of an earlier filing date of and the right of priority to Korean Application No. 10-2018-0041124, filed on Apr. 9, 2018, the contents of which are incorporated by reference herein in their entirety.

BACKGROUND OF THE DISCLOSURE 1. Field of the Disclosure

The present invention relates to a motor operated compressor operated by a motor.

2. Background Art

A motor operated compressor mainly employs a scroll compression method suitable for a high compression ratio operation among various compression methods. In the scroll type motor operated compressor, a motor unit configured as a rotary motor is installed in a hermetic casing, and a compression unit configured by a fixed scroll and an orbiting scroll is disposed at one side of the motor unit. The motor unit and the compression unit are connected to each other by a rotation shaft so that a rotational force of the motor unit is transferred to the compression unit. The rotational force transmitted to the compression unit causes the orbiting scroll to perform an orbiting motion with respect to the fixed scroll, so as to form a pair of compression chambers each having a suction chamber, an intermediate pressure chamber, and a discharge chamber, so that a refrigerant is sucked into each of the compression chambers, compressed therein, and then simultaneously discharged.

The scroll type compressor applied to an air conditioning system for a vehicle is mainly installed generally horizontally in view of a structure of an engine room of the vehicle. A motor unit and a compression unit are arranged in a horizontal direction and connected to each other by a rotation shaft. Accordingly, a main frame and a sub frame are provided for supporting the rotation shaft on both lateral sides of the motor unit, and the main frame is provided with a main bearing for supporting a center portion of the rotation shaft. The sub frame is provided with a sub bearing for supporting an end portion of the rotation shaft.

However, in the related art motor operated compressor, as described above, the main frame is located between a driving motor and the compression unit, and the main bearing provided at the main frame radially supports a middle portion of the rotation shaft. Accordingly, the main frame requires a space for accommodating the main bearing, which increases an axial length of the main frame, thereby increasing an overall axial length of the compressor.

In the related art motor operated compressor, oil is separated from a refrigerant discharged from a compression chamber into a discharge space, and the separated oil is supplied to the compression chamber or bearing surfaces through an oil supply passage provided in a scroll or frame. However, it is difficult to form the oil supply passage in the scroll or frame, and also the oil supply passage becomes long. If the oil supply passage becomes long, oil is not quickly supplied when the compressor is turned on, thereby causing a frictional loss.

In addition, in the related art motor operated compressor, a ball bearing is used to suppress the rotation shaft from being pushed in an axial direction. However, costs and operation noise increase due to the ball bearing and a weight of the compressor increases due to a weight of the ball bearing.

SUMMARY OF THE INVENTION

One aspect of the present invention is to provide a motor operated compressor, capable of reducing a length and weight of the compressor by reducing a length of a frame in a manner of excluding a bearing from the frame.

Another aspect of the present invention is to provide a motor operated compressor, capable of excluding a bearing from a frame by supporting both ends of a rotation shaft in a structure that radially supports the rotation shaft at both horizontal sides of a motor unit.

Still another aspect of the present invention is to provide a motor operated compressor, capable of facilitating a formation of an oil supply passage for guiding oil toward a compression unit or a bearing surface and also allowing a fast supply of oil by reducing a length of the oil supply passage.

Still another aspect of the present invention is to provide a motor operated compressor, capable of reducing costs and operation noise caused due to a bearing supporting a rotation shaft, and lowering a weight of the compressor.

In order to achieve the aspects of the present invention, there is provided a motor operated compressor, including a casing, a frame provided inside the casing, a driving motor provided at one side of the frame, a compression unit provided at another side of the frame, and a rotation shaft to transfer a rotational force of the driving motor to the compression unit, wherein one end portion of the rotation shaft is supported by the compression unit or one side of the casing through the frame, and another end portion of the rotation shaft is supported by another side of the casing.

Here, the compression unit may form a compression chamber as a plurality of scrolls are engaged with each other, and one end of the rotation shaft may be inserted through one of the plurality of scrolls and may be supported by another scroll in a radial direction.

In this case, the compression unit may form a compression chamber as the plurality of scrolls are engaged with each other, and one end of the rotation shaft may be inserted through the plurality of scrolls and may be supported by an inner wall surface of the casing in the radial direction.

Here, both ends of the rotation shaft may be supported by a bush bearing, a balance weight may be coupled to the rotation shaft, and the balance weight may be axially supported by the frame.

And, the casing may include an oil separation space therein in which oil is separated from a refrigerant discharged from the compression chamber. The rotation shaft may be provided with an oil supply passage communicating with the oil separation space such that oil from the oil separation space is guided to the compression chamber and a bearing surface.

Further, in order to achieve those aspects and other advantages of the present invention, there is provided a motor operated compressor, including a driving motor having a stator and a rotor, a rotation shaft coupled to the rotor, a frame provided on one side of the driving motor in an axial direction, an orbiting scroll supported on the frame in an axial direction and eccentrically coupled to the rotation shaft to perform an orbiting motion, a fixed scroll provided at an opposite side of the frame with the orbiting scroll interposed therebetween to form a compression chamber together with the orbiting scroll. One end portion of the rotation shaft, penetrating through the frame and the orbiting scroll, may be supported in a radial direction. A casing may be provided at an opposite side of the frame with the driving motor interposed therebetween. The casing may support another end portion of the rotation shaft in the radial direction.

Here, the fixed scroll may be provided with a first shaft supporting portion protruding therefrom so that the one end portion of the rotation shaft is rotatably inserted in the protruding portion. The first shaft supporting portion may be provided with a first bearing disposed on an inner circumferential surface thereof to support the one end portion of the rotation shaft.

The casing may be provided with a second shaft supporting portion protruding therefrom in a direction toward the driving motor, so that the another end portion of the rotation shaft is rotatably inserted into the protruding portion of the casing, and the second shaft supporting portion may be provided with a second bearing disposed on an inner circumferential surface thereof to support the another end portion of the rotation shaft.

The frame may be provided with a frame shaft hole through which the rotation shaft is inserted, and a gap between an inner circumferential surface of the frame shaft hole and an outer circumferential surface of the rotation shaft may be larger than a gap between an inner circumferential surface of the first bearing and the outer circumferential surface of the rotation shaft or a gap between an inner circumferential surface of the second bearing and the outer circumferential surface of the rotation shaft.

The frame may be provided with a first space portion formed on one side surface thereof and forming a first back pressure space together with the orbiting scroll, and a sealing member for sealing the first back pressure space may be provided between the inner circumferential surface of the frame shaft hole and the outer circumferential surface of the rotation shaft.

Here, the fixed scroll may be provided with a first bearing for supporting a first bearing portion of the rotation shaft, the casing may be provided with a second bearing for supporting a second bearing portion of the rotation shaft, and the orbiting scroll may be provided with a third bearing for supporting an eccentric portion of the rotation shaft. The first bearing may be a bush bearing or a needle bearing, the second bearing may be a bush bearing or a ball bearing, and the third bearing may be a bush bearing.

Here, the rotation shaft may be provided with a first bearing portion formed on the one end portion thereof and supported by the fixed scroll, a second bearing portion formed on the another end portion thereof and supported by the casing, and an eccentric portion formed between the first bearing portion and the second bearing portion to be eccentrically coupled through the orbiting scroll. A balance weight may be coupled between the second bearing portion and the eccentric portion of the rotation shaft, and supported in the axial direction by being in contact with the frame.

The frame may be provided with a first space portion formed on one side surface thereof and forming a first back pressure space together with the orbiting scroll. The first space portion may be provided with a bearing supporting protrusion protruding in the axial direction toward the balance weight so as to form a bearing surface with the balance weight in the axial direction.

The rotation shaft may be provided with an axial supporting surface formed on an outer circumferential surface thereof in a stepped manner to support the balance weight in the axial direction.

The casing may be provided with a second shaft supporting portion protruding therefrom in a direction toward the driving motor, so that the another end portion of the rotation shaft is rotatably inserted into the protruding portion of the casing. The second shaft supporting portion may be provided therein with a second space portion spaced apart from an end portion of the rotation shaft and storing a part of oil discharged from the compression chamber.

The casing may be provided therein with an oil storage portion to store oil which is discharged together with a refrigerant from the compression chamber and then separated from the refrigerant. The oil storage portion may be provided with an oil supply passage formed between the oil storage portion and the another end portion of the rotation shaft in a penetrating manner to guide the oil in the oil storage portion to a bearing surface.

The oil supply passage may be provided with at least one pressure-reducing portion.

The casing may be provided with a second shaft supporting portion protruding therefrom in a direction toward the driving motor, so that the another end portion of the rotation shaft is rotatably inserted into the protruding portion of the casing. The second shaft supporting portion may overlap a coil wound around the stator in a radial direction.

The frame may be provided with a first space portion forming a first back pressure space together with the orbiting scroll, and the first space portion may overlap at least part of a coil wound around the stator in the radial direction.

The rotation shaft may be provided with a balance weight coupled thereto, and the balance weight may overlap at least part of a coil wound around the stator in the radial direction.

Further, in order to achieve the aspects and other advantages of the present invention, there is provided a motor operated compressor, including, a driving motor having a stator and a rotor; a rotation shaft coupled to the rotor to transfer a rotational force of the driving motor to the rotor; a frame having a frame shaft hole so that the rotation shaft is rotatably penetrated through the frame; an orbiting scroll supported on the frame in an axial direction and having a rotation shaft coupling portion so that the rotation shaft is coupled to be eccentrically penetrated through the orbiting scroll; a fixed scroll provided at an opposite side of the frame with the orbiting scroll interposed therebetween to form a compression chamber together with the orbiting scroll, the fixed scroll having a scroll shaft hole so that the rotation shaft is rotatably penetrated through the fixed scroll; a first shaft supporting portion provided on an inner surface of the casing forming a discharge space together with the fixed scroll, so as to support one end portion of the rotation shaft penetrated through the frame shaft hole, the shaft coupling portion of orbiting scroll, and the scroll shaft hole of the fixed scroll; and a second shaft supporting portion provided at an opposite side of the frame with the driving motor interposed therebetween to support another end portion of the rotation shaft in the radial direction.

In a motor operated compressor according to the present invention, one end of a rotation shaft can be supported by a scroll or a casing and another end thereof by the casing while supporting the rotation shaft at both sides of a driving motor, thereby reducing a length of the rotation shaft and simultaneously reducing an overall axial length of the compressor.

In a motor operated compressor according to the present invention, both ends of a rotation shaft can be supported while radially supporting the rotation shaft at both sides of a driving motor in a horizontal direction, which may allow a bearing for radially supporting the rotation shaft to be excluded from a frame and accordingly make a gap between a compression unit and the driving motor narrow, thereby reducing an overall weight and length of the compressor.

Further, in a motor operated compressor according to the present invention, an oil supply passage can be formed in a rotation shaft, which can facilitate a formation of the oil supply passage for guiding oil to a compression unit or a bearing surface and also allow a reduction of a length of the oil supply passage so as to enable a quick supply of oil.

In addition, in a motor operated compressor according to the present invention, since a balance weight coupled to a rotation shaft can be supported by a frame so as to support the rotation shaft in an axial direction, a bush bearing which is relatively less expensive, causes less operation noise, and has a higher assembly property than a ball bearing can be applied. This may result in reducing fabricating costs, noise and weight of the compressor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of a motor operated compressor in accordance with the present invention.

FIG. 2 is a planar view illustrating a coupling relationship between a fixed scroll and an orbiting scroll, which is a horizontal sectional view of a compression unit in FIG. 1.

FIG. 3 is an enlarged sectional view illustrating a rotation shaft in accordance with an embodiment of the present invention.

FIG. 4 is an enlarged sectional view illustrating a part of a compression unit in accordance with an embodiment of the present invention.

FIG. 5 is an enlarged sectional view illustrating a first shaft supporting portion in accordance with an embodiment of the present invention.

FIG. 6 is an enlarged sectional view illustrating a second shaft supporting portion in accordance with an embodiment of the present invention.

FIG. 7 is a schematic view illustrating an oil supply passage in a scroll compressor according to the present invention.

FIG. 8 is a sectional view illustrating one example of an axial bearing in accordance with an embodiment of the present invention.

FIGS. 9 and 10 are sectional views illustrating different embodiments of an axial supporting structure according to the present invention.

FIG. 11 is a sectional view illustrating another embodiment of a frame according to the present invention.

FIG. 12 is a sectional view illustrating another embodiment of a first shaft supporting portion according to the present invention.

DETAILED DESCRIPTION

Description will now be given in detail of a motor operated compressor according to exemplary embodiments disclosed herein, with reference to the accompanying drawings.

FIG. 1 is a sectional view illustrating an inside of a motor operated compressor in accordance with the present invention.

As illustrated in FIG. 1, a low-pressure motor operated scroll compressor (hereinafter, abbreviated as motor operated compressor) according to an embodiment of the present invention includes a frame 102 fixed to an inside of a compressor casing (hereinafter, abbreviated as a casing) 101, a driving motor 103 serving as a motor unit provided at one side of the frame 102 based on the frame 102, and a compression unit 105 provided at another side of the frame 102 to compress a refrigerant using a rotational force of the driving motor 103.

As the casing 101 is arranged in a generally horizontal direction with respect to the ground, the driving motor 103 and the compression unit 105 are also arranged in the generally horizontal direction. For the sake of explanation, a right side of FIG. 1 is designated as a front side and a left side as a rear side.

The casing 101 includes a main housing 111 in which the frame 102, the driving motor 103 and the compression unit 105 are installed, and a rear housing 112 coupled to an open rear end of the main housing 111 in a covering manner. The main housing 111 is provided with an inlet port 101 a and the rear housing 112 is provided with an exhaust port 101 b. Also, a suction space S1 is formed in the main housing 111 and a discharge space S2 is formed in the rear housing 112.

The frame 102 is coupled to a front opening of the main housing 111 and a first scroll 150 to be described later is fixedly supported on a rear surface of the frame 102. A second scroll 160 to be explained later is rotatably supported on the rear surface of the frame 102 so as to perform an orbiting motion between the first scroll 150 and the frame 102.

The driving motor 103 includes a stator 131 fixed to an inside of the main housing 111, a rotor 132 located inside the stator 131 and rotated by interaction with stator 131, and a rotation shaft 133 coupled to the rotor 132 to transfer a rotational force of the driving motor 103 to the compression unit 105 while rotating together with the rotor 132.

The compression unit 105 includes a fixed scroll (hereinafter, referred to as a first scroll) 150 supported by the frame 102, and an orbiting scroll (hereinafter, referred to as a second scroll) 160 provided between the frame 102 and the first scroll 150 to form a pair of compression chambers V together with the first scroll 150 while performing an orbiting motion. An Oldham ring 170 which is a rotation-preventing mechanism for preventing rotation of the second scroll 160 coupled to the rotation shaft 133 is provided between the frame 102 and the second scroll 160.

The first scroll 150 includes a fixed scroll disk portion (hereinafter, referred to as a fixed disk portion) 151 formed substantially in a disk shape, and a side wall portion 152 formed at an edge of the fixed disk portion 151 to be coupled to a frame side wall portion 122. A fixed wrap 153 which is engaged with an orbiting wrap 162 to be explained later so as to form the compression chambers is formed on a front surface of the fixed disk portion 151.

A suction flow path 154 is formed at one side of the scroll side wall portion 152 so that the suction space S1 and a suction chamber (not shown) communicate with each other. An outlet port 155 is formed at a central part of the fixed disk portion 151 and communicates with a discharge chamber so that a compressed refrigerant is discharged to the discharge space S2. Only one outlet port 155 may be formed to communicate a first compression chamber V1 and a second compression chamber V2 to be explained later, or a first outlet port 155 a and a second outlet port 155 b may be formed to communicate with the first compression chamber V1 and the second compression chamber V2, respectively.

The second scroll 160 is provided with an orbiting scroll disk portion (hereinafter, referred to as an orbiting disk portion) 161 formed substantially in a disk shape, and an orbiting wrap 162 which is engaged with the fixed wrap 153 to form the compression chambers is formed on a rear surface of the orbiting disk portion 161. The orbiting wrap 162 may be formed in an involute shape together with the fixed wrap 153, but may also be formed in various other shapes. The shape of the orbiting wrap 162 will be described later together with the fixed wrap 153, with reference to FIG. 2.

That is, when power is applied to the driving motor 103 of the scroll compressor, the rotation shaft 133 transfers a rotational force to the second scroll 160 while rotating together with the rotor 132, and the second scroll 160 performs an orbiting motion by the Oldham ring 170. Then, the compression chamber V is reduced in volume while continuously moving toward a center.

A refrigerant flows into the suction space S1 through the inlet port 101 a and passes through a flow path formed between an outer circumferential surface of the stator 131 and an inner circumferential surface of the main housing 111 or a gap between the stator 131 and the rotor 132. Such refrigerant is then introduced into the compression chamber V through the suction flow path 154.

This refrigerant is compressed by the first scroll 150 and the second scroll 160 and is discharged into the discharge space S2. The refrigerant is separated from oil in the discharge space S2. Accordingly, the refrigerant is discharged to a refrigeration cycle through the exhaust port 101 b while the oil is supplied to the compression chambers and each bearing surface through an oil supply passage Fo to be explained later. Such series of processes are repeated.

Considering that the scroll compressor according to this embodiment is applied to a vehicle in view of its characteristics, it is important to reduce a weight of the compressor. However, in the related art scroll compressor, since the main frame and the sub frame were provided at both sides of the driving motor to support the rotation shaft in a radial direction, an overall length of the compressor became longer.

The length of the compressor can be minimized by reducing a length of the frame, and accordingly an overall weight of the compressor can be reduced. Further, a load axially applied to the rotation shaft can be endured even while using a bush bearing that is lighter than a ball bearing, and thus the overall weight of the compressor can be reduced.

For this purpose, a so-called shaft-through scroll compressor type in which a rotation shaft is coupled through an orbiting scroll as shown in the embodiment of the present invention may be applied. That is, the shaft-through scroll compressor, as aforementioned, is configured in a manner that the rotation shaft is coupled through the orbiting scroll. Accordingly, when the rotation shaft further extends, an end portion of the rotation shaft may be inserted into the fixed scroll or the rear housing so as to be supported in a radial direction. Therefore, since one side of the rotation shaft can be supported even if the rotation shaft is not supported by the frame, a main bearing can be removed from the frame.

Normally, in a scroll compressor including a shaft-through scroll compressor, a fixed wrap and an orbiting wrap are formed in an involute shape, but may alternatively be formed in a non-involute shape, as shown in the embodiment of the present invention. FIG. 2 is a planar view illustrating a coupling relationship between a fixed scroll and an orbiting scroll, which is a horizontal sectional view of the compression unit in FIG. 1.

As illustrated in FIG. 2, the orbiting wrap 162 according to the embodiment of the present invention may have a shape in which a plurality of arcs having different diameters and origins are connected, and the outermost curve may be formed substantially in an elliptical shape having a major axis and a minor axis. A fixed wrap 153 may be formed in a similar manner.

A rotation shaft coupling portion 163 which forms an inner end portion of the orbiting wrap 162 and to which an eccentric portion 133 a of the rotation shaft 133 to be explained later is rotatably inserted may be formed through a central part of the orbiting disk portion 161 in an axial direction. An outer circumferential part of the rotation shaft coupling portion 163 is connected to the orbiting wrap 162 to form the compression chamber V together with the fixed wrap 153 during a compression process.

Furthermore, the rotation shaft coupling portion 163 may be formed at a height overlapping the orbiting wrap 162 on the same plane, and thus the eccentric portion 133 a of the rotation shaft 133 may be disposed at a height overlapping the orbiting wrap 162 on the same plane. Accordingly, a repulsive force and a compressive force of a refrigerant are attenuated by each other while being applied to the same plane based on the orbiting disk portion, thereby preventing an inclination of the second scroll 160 due to an action of the compressive force and repulsive force.

The rotation shaft coupling portion 163 is provided with a concave portion 163 a formed on an outer circumferential part thereof, which faces an inner end portion of the fixed wrap 153, and engaged with a protrusion 153 a of the fixed wrap 153 to be explained later. An increasing portion 163 b which increases in thickness from an inner circumferential part to the outer circumferential part of the rotation shaft coupling portion 163 is formed at an upstream side along a direction that the compression chamber V is formed. This may extend a compression path of the first compression chamber V1 immediately before discharge, and consequently a compression ratio of the first compression chamber V1 can be increased close to a compression ratio of the second compression chamber V2.

At another side of the concave portion 163 a is formed an arcuate compression surface 163 c having an arcuate shape. A diameter of the arcuate compression surface 163 c is decided by a thickness of the inner end portion of the fixed wrap 153 (i.e., a thickness of a discharge end) and an orbiting radius of the orbiting wrap 162. When the thickness of the inner end portion of the fixed wrap 153 increases, a diameter of the arcuate compression surface 163 c increases. As a result, a thickness of the orbiting wrap around the arcuate compression surface 163 c may increase to ensure durability, and the compression path may extend to increase the compression ratio of the second compression chamber V2 to that extent.

In addition, the protrusion 153 a protruding toward the outer circumferential part of the rotation shaft coupling portion 163 may be formed adjacent to the inner end portion (a suction end or starting end) of the fixed wrap 153 corresponding to the rotation shaft coupling portion 163. The protrusion 153 a may be provided with a contact portion 153 b protruding therefrom and engaged with the concave portion 163 a. In other words, the inner end portion of the fixed wrap 153 may be formed to have a larger thickness than other portions. As a result, wrap strength at the inner end portion of the fixed wrap 153, which is subjected to the highest compressive force on the fixed wrap 323, may increase so as to enhance durability.

On the other hand, the compression chamber V may be formed by the fixed disk portion 151, the fixed wrap 153, the orbiting wrap 162 and the orbiting disk portion 161, and a suction chamber, an intermediate pressure chamber, and a discharge chamber may be formed consecutively along a proceeding direction of the wraps.

The compression chamber V may include a first compression chamber V1 formed between an inner surface of the fixed wrap 153 and an outer surface of the orbiting wrap 162, and a second compression chamber V2 formed between an outer surface of the fixed wrap 153 and an inner surface of the orbiting wrap 162. In other words, the first compression chamber V1 includes a compression chamber formed between two contact points P11 and P12 generated in response to the inner surface of the fixed wrap 153 being brought into contact with the outer surface of the orbiting wrap 162, and the second compression chamber V2 includes a compression chamber formed between two contact points P21 and P22 generated in response to the outer surface of the fixed wrap 153 being brought into contact with the inner surface of the orbiting wrap 162.

Here, two lines, which connect a center of the eccentric portion, namely, a center O of the rotation shaft coupling portion to the two contact points P11 and P12, respectively, define an angle α within the first compression chamber V2 just before discharge. The angle α at least just before the discharge is larger than 360° (i.e., α<360°), and a distance l between normal vectors at the two contact points (P11, P12) also has a value greater than zero.

As a result, the first compression chamber immediately before the discharge, which is formed by the fixed wrap and the orbiting wrap according to the embodiment of the present invention, may have a smaller volume than that formed by a fixed wrap and an orbiting wrap having an involute shape. Therefore, the compression ratios of the first and second compression chambers V1 and V2 can all be improved even without increasing the size of the fixed wrap 153 and the orbiting wrap 162.

Hereinafter, an overall configuration of a motor operated compressor for supporting both ends of a rotation shaft in a radial direction in a scroll compressor having the aforementioned compression unit will be described. As described above, in order to support both ends of the rotation shaft, one end of the rotation shaft, passing through the second scroll, may be inserted into the first scroll, or may be inserted into the rear housing through the first scroll. Thus, in the present invention, the former will be described first, and the latter will be described later as another embodiment.

Referring back to FIG. 1, the main housing 111 is provided with a cylindrical portion 111 a. A front end of the cylindrical portion 111 a integrally extends to form a closed front portion 111 b, and a rear end of the cylindrical portion 111 a is opened such that the rear housing 112 is hermetically coupled thereto.

A second shaft supporting portion 111 c is formed in a cylindrical shape on an inner surface of the front portion 111 b. And a second bearing portion 133 e of the rotation shaft to be explained later is inserted into the second shaft supporting portion 111 c to be supported in a radial direction.

The rear housing 112 is coupled to the cylindrical portion 111 a of the main housing 111 to seal the inside of the casing 101. The discharge space S2 is formed in the rear housing 112 and the exhaust port 101 b is formed at one side of the discharge space S2. An oil separator (not shown) for separating oil from a discharged refrigerant is separately provided in the exhaust port 101 b or near the exhaust port 101 b, or an oil separating unit is provided without a separate oil separator.

Here, in the discharge space S2, an oil separation portion S21 for separating oil from a refrigerant discharged from the compression chamber is disposed at an upper half part, and an oil storage portion S22 for storing the oil separated in the oil separation portion S21 is disposed at a lower half part. The oil storage portion S22 communicates with the compression unit 105 through an oil supply passage Fo to be described later so that the oil in the oil storage portion S22 is supplied to the compression unit 105 or the rotation shaft 133. The oil supply passage will be described later together with the rotation shaft.

The driving motor 103 is installed at the front with respect to the frame 102 and the stator 131 is provided with a winding coil 131 a wound around the stator core 131 b so as to receive external power. Afront end 131 a 1 of the winding coil 131 a may radially overlap the second shaft supporting portion 111 c while a rear end 131 a 2 of the winding coil 131 a may radially overlap a first space portion 124 of the frame 102 which forms a first back pressure space S3 by a predetermined length t4. This is because a gap between the driving motor 103 and the frame 102 can be further narrowed as a radial bearing surface is removed from the frame 102. However, the front end 131 a 1 of the winding coil 131 a may not necessarily overlap the second shaft supporting portion 111 c in the radial direction, but it is preferable that the front end 131 a 1 of the winding coil 131 a overlaps at least part of the frame 102.

The rotor 132 is rotatably inserted into the stator 131 with a predetermined gap therebetween and the rotation shaft 133 is press-fitted into an inner circumferential surface of the rotor 132.

FIG. 3 is an enlarged sectional view illustrating a rotation shaft according to an embodiment of the present invention, and FIG. 4 is an enlarged sectional view illustrating a part of a compression unit according to an embodiment of the present invention.

As illustrated in the drawings, the rotation shaft 133 may be divided into a first shaft portion 133 a, a second shaft portion 133 b, an eccentric portion 133 c, a first bearing portion 133 d, and a second bearing portion 133 e.

The first shaft portion 133 a and the second shaft portion 133 b may be formed consecutively in a direction from the driving motor toward the compression unit and the second shaft portion 133 b may have a larger diameter than the first shaft portion 133 a. The first shaft portion 133 a is press-fitted into a rotor core constituting the rotor 132 and the second shaft portion 133 b is coupled through a frame shaft hole 125 (see FIG. 8). Accordingly, outer circumferential surfaces of the first shaft portion 133 a and the second shaft portion 133 b do not form a radial bearing surface.

Here, since the outer circumferential surface of the second shaft portion 133 b does not form the radial bearing surface, a length L2 of the second shaft portion 133 b may be shorter than a length L1 of the first shaft portion 133 a. As a result, a gap between the driving motor and the compression unit can be narrowed, and an overall length of the compressor can be reduced accordingly.

The eccentric portion 133 c extends eccentrically from the second shaft portion 133 b to one end portion (hereinafter, referred to as a first end portion) of the rotation shaft 133, and is coupled through the rotation shaft coupling portion 163 of the second scroll 160. A third bearing 183 configured as a bush bearing is coupled to an inner circumferential surface of the rotation shaft coupling portion 163 in an inserted manner, and an inner circumferential surface of the third bearing 183 forms a radial bearing surface with an outer circumferential surface of the eccentric portion 133 c.

The first bearing portion 133 d further extends from the eccentric portion 133 c toward the first end portion so as to be rotatably inserted into the first shaft supporting portion 151 a of the first scroll 150. A first bearing 181 configured as a bush bearing is coupled to an inner circumferential surface of the first shaft supporting portion 151 a and an inner circumferential surface of the first bearing 181 forms a radial bearing surface together with an outer circumferential surface of the first bearing portion 133 d.

The second bearing portion 133 e extends from the first shaft portion 133 a toward the front portion 111 b of the main housing 111 so as to be rotatably inserted into the second shaft supporting portion 111 c. A second bearing 182 configured as a bush bearing is coupled to an inner circumferential surface of the second shaft supporting portion 111 c in an inserted manner, and an inner circumferential surface of the second bearing 182 forms a radial bearing surface together with an outer circumferential surface of the second bearing portion 133 e.

On the other hand, as illustrated in FIG. 4, the frame 102 is located between the driving motor 103 and the compression unit 105 and supports the second scroll 160 in an axial direction.

In addition, the frame 102 is provided with a frame disk portion 121 formed in a disk shape. A frame side wall portion 122 to which the side wall portion 152 of the first scroll 150 is coupled is formed on a rear edge of the frame disk portion 121. A first space portion 124 forming a first back pressure space S3 to be explained later is recessed on a rear central portion of the frame disk portion 121.

A frame thrust surface 123 on which the second scroll 160 is placed to be supported in an axial direction may be formed on an inner side of the frame side wall portion 122, and a first sealing member 191 for supporting the first back pressure space S3 may be provided on the frame thrust surface 123. Since the first sealing member 191 is provided on the thrust surface between the frame 102 and the second scroll 160, the first sealing member 191 may alternatively be provided on a rear surface of the second scroll 160.

Here, the first back pressure space S3 is a space formed between the first space portion 124 of the frame 102 and the orbiting disk portion 161 of the second scroll 160 facing the first space portion 124. A part of a refrigerant compressed in the compression chamber V is filled together with oil in the first back pressure space S3 in a manner of being depressurized by a predetermined degree. Therefore, pressure in the first back pressure space S3 is intermediate pressure between pressure in the suction space S1 and final pressure (i.e., discharge pressure) of the compression chamber V, and the rear surface of the second scroll 160 is supported by back pressure of the first back pressure chamber S3.

A frame shaft hole 125 through which the rotation shaft 133 is inserted is formed in a middle of the first space portion 124 forming the first back pressure space S3. A second sealing member 192 may be provided on an inner circumferential surface of the frame shaft hole 125 to seal a gap between the inner circumferential surface of the frame shaft hole 125 and an outer circumferential surface of the rotation shaft 133, more accurately, an outer circumferential surface of the second shaft portion 133 b. To this end, a second sealing groove 125 a in an annular shape may be formed at the inner circumferential surface of the frame shaft hole 125, and the second sealing member 192, which also has the annular shape, may be inserted into the second sealing groove 125 a. A fixing plate 195 for supporting the second sealing member 192 may be provided at an outside of the second sealing member 192 so as to be fixed to an outer surface of the frame 102 while supporting the second sealing member 192 in an axial direction.

However, in some cases, the second sealing member may be inserted into the second shaft portion 133 b of the rotation shaft 133, or the second sealing member may be excluded. When the second sealing member is excluded, one end of the first back pressure space S3 is finely opened so that oil or refrigerant flowing into the first back pressure space S3 may leak. However, the leakage of the oil or the refrigerant can be minimized when a gap between the frame shaft hole 125 and the rotation shaft 133 is made fine or a sealing portion such as a labyrinth seal is formed. This may prevent the oil or the refrigerant from stagnating in the first back pressure space S3, which may result in providing an effect that new oil or refrigerant can be continuously introduced into the first back pressure space S3.

Further, a separate bearing for supporting the rotation shaft 133 in a radial direction is not provided on the inner circumferential surface of the frame shaft hole 125. An inner diameter D1 of the frame shaft hole 125 is larger than an outer diameter D2 of the second shaft portion 133 b of the rotation shaft 133. Accordingly, a third gap t3 between the inner circumferential surface of the frame shaft hole 125 and the outer circumferential surface of the second shaft portion 133 b is larger than a first gap t1 between an inner circumferential surface of the first bearing 181 and an outer circumferential surface of the first bearing portion 133 d or a second gap t2 between an inner circumferential surface of the second bearing 182 and an outer circumferential surface of the second bearing portion 133 e. Therefore, the frame shaft hole 125 does not support the second shaft portion 133 b of the rotation shaft 133 in the radial direction, but merely serves as a passage for allowing the rotation shaft 133 to penetrate through the frame 102.

As described above, since the frame 102 only plays the role of supporting the first scroll 150 and the second scroll 160, an axial height H1 of the frame 102 may be the same as or smaller than an axial height H2 of the first scroll 150. However, since the axial height H2 of the first scroll 150 may differ depending on a capacity of the compressor, the axial height H1 of the frame is not always the same as or smaller than the axial height H2 of the first scroll 150. Particularly, if the first shaft supporting portion is not formed in the first scroll, the axial height of the first scroll becomes as low as that, and thus may become similar to the axial height of the frame. As the axial height H1 of the frame 102 is reduced, the axial length of the rotation shaft 133 is also reduced. And, as the axial length of the rotation shaft 133 is reduced, an overall axial length of the compressor can be reduced as well.

On the other hand, an axial supporting protrusion 126, which forms an axial bearing surface together with a balance weight 135 to be explained later, may be formed on one side surface of the frame shaft hole 125, namely, an end portion of the frame shaft hole 125 which forms the first space portion 124. This will be described later again together with an axial supporting structure.

As described above, since the second shaft portion 133 b located at the middle of the rotation shaft 133 is coupled through the frame 102 without being radially supported by the frame 102, the first bearing portion 133 d and the second bearing portion 133 e which form both ends of the rotation shaft 133 are radially supported by the first shaft supporting portion 151 a provided on the first scroll 150 and the second shaft supporting portion 111 c provided on the front portion 111 b of the main housing 111.

FIG. 5 is an enlarged sectional view illustrating a first shaft supporting portion in accordance with an embodiment of the present invention, and FIG. 6 is an enlarged sectional view illustrating a second shaft supporting portion in accordance with an embodiment of the present invention.

As illustrated in FIGS. 3 and 5, the first shaft supporting portion 151 a is formed to protrude from a central part of the fixed disk portion 151 of the first scroll 150 toward the rear side, that is, toward the rear housing 112. The first shaft supporting portion 151 a may be formed by increasing a thickness of the fixed disk portion 151. However, in this case, the weight of the compression unit 105 increases. Thus, it may be preferable to form the first shaft supporting portion 151 a to protrude from a rear surface of the fixed disk portion 151 toward the discharge space S2 into a cylindrical shape by a predetermined height.

The first shaft portion 151 a, as aforementioned, is provided with the first bearing 181 configured as the bush bearing, so as to form a first radial bearing surface together with the first bearing portion 133 d of the rotation shaft 133. However, the first bearing 181 is not limited only to the bush bearing. That is, the first bearing 181 may alternatively be a needle bearing. In the case of the needle bearing, the first bearing 181 can also be used as an axial bearing, so as to suppress the rotation shaft 133 from being pushed toward another end portion (hereinafter, referred to as a second end portion) to some extent.

As illustrated in FIGS. 3 and 6, the second shaft supporting portion 111 c is formed in a cylindrical shape by protruding from an inner surface of the front portion 111 b of the main housing 111 toward the driving motor 103 by a predetermined axial height. At this time, the second shaft supporting portion 111 c preferably extends to an axial height such that it is disposed adjacent to the driving motor 103, that is, the second shaft supporting portion 111 c preferably extends to an axial height such that it overlaps a front end 131 a 1 of the winding coil 131 a wound around the stator core 131 b. As a result, the front portion 111 b can be formed as close as possible to the driving motor 103, thereby reducing the length of the compressor.

The second shaft supporting portion 111 c, as aforementioned, is provided with the second bearing 182 configured as the bush bearing, so as to form a second radial bearing surface together with the second bearing portion 133 e of the rotation shaft 133. However, the second bearing 182 is not limited only to the bush bearing. That is, the second bearing 182 may alternatively be a ball bearing. The ball bearing can also be used as an axial bearing, so as to effectively suppress the rotation shaft 133 from being pushed toward the second end portion.

In this way, the first bearing portion which supports one end of the rotation shaft in the radial direction is provided on the fixed scroll located at one side of the driving motor, and the second bearing portion which supports another end of the rotation shaft in the radial direction is provided on the casing located at another side of the driving motor. Accordingly, a bearing which is provided on the frame to support the rotation shaft can be removed, and thus an axial length and weight of the frame can be reduced, which may result in reducing an axial length and weight of the compressor.

In addition, when the first bearing and the second bearing as well as the third bearing are each configured as a bush bearing, fabricating costs and operation noise due to the bearings can be reduced and the weight of the compressor can be decreased.

On the other hand, the scroll compressor separates oil from a refrigerant discharged from the compression chamber and guides a part of the oil to the compression chambers or each bearing surface to lubricate a friction surface. To this end, an oil supply passage for guiding oil stored in the oil storage portion of the discharge space may be formed in the casing. FIG. 7 is a schematic view illustrating an oil supply passage in a scroll compressor according to the present invention.

As illustrated in FIGS. 3 and 7, a communication hole 151 b for communicating an inner space of the first shaft supporting portion 151 a with the oil storage portion S22 is formed at the first shaft supporting portion 151 a, and an oil supply pipe 141 coupled toward the oil storage portion S22 may be connected to the communication hole 151 b. However, the present invention is not limited to the oil supply pipe, and an oil supply groove may alternatively be formed at a rear surface of the first scroll 150 or the rear housing 112 to be connected to the communication hole 151 b.

An oil flow path 142 constituting a part of the oil supply passage Fo is formed inside the rotation shaft 133. A plurality of oil supply holes 142 a and 142 b are formed in a middle part of the oil flow path 142 along a lengthwise direction with a predetermined interval.

The oil flow path 142 may be formed to penetrate through both ends of the rotation shaft 133 or may be formed up to a middle position of the rotation shaft 133. However, in order for oil to smoothly flow into the oil flow path 142, it is advantageous to form an oil discharge hole 142 c in the oil flow path 142. In this case, the oil discharge hole 142 c may be formed in the oil flow path 142 to communicate with the first back pressure chamber S3 or the suction space S1. FIG. 7 is a view showing an example in which the oil discharge hole 142 c is formed in the oil flow path 142 to communicate with the suction space.

The plurality of oil supply holes 142 a and 142 b may be formed in a radial direction and extending from the oil flow path 142 toward each outer circumferential surface of the first bearing portion 133 d, the eccentric portion 133 c, and the second bearing portion 133 e, so that oil flowing along the oil flow path 142 can be guided to each bearing surface. The plurality of oil supply holes 142 a and 142 b may be formed within an axial range of each of the bearing portions 133 d and 133 e and the eccentric portion 133 c corresponding to the oil supply holes. However, since the second bearing 182 is exposed to the suction space S1 of the casing 101, the second bearing 182 may be lubricated by a refrigerant and oil flowing into the suction space even without forming any additional oil supply hole.

On the other hand, a pressure-reducing portion may be formed in the oil supply passage Fo. That is, an inlet of the oil supply passage Fo communicates with the discharge space S2 (precisely, the oil storage portion) which is a high-pressure portion, while an outlet of the oil supply passage Fo communicates with the suction space S1 which is a low-pressure portion. Accordingly, if the pressure-reducing portion is not provided in the oil supply passage, oil in the discharge space may excessively flow out from the oil storage portion S22 of the discharge space S2 to the suction space S1.

In view of this, a pressure-reducing member 143 such as a pressure-reducing rod is inserted into the oil flow path 142 constituting the oil supply passage F0 to reduce an inner diameter of the oil flow path 142, so that pressure of oil passing through a pressuring-reducing section can be lowered to intermediate pressure. The pressure-reducing member may be provided not only inside the rotation shaft 133 but also at any position if it is located more upstream than the oil supply holes 142 a and 142 b.

Accordingly, oil collected in the oil storage portion S22 flows into the oil flow path 142 through the oil supply passage Fo due to a pressure difference between the discharge space S2 and the suction space S1, and then is supplied to the compression chamber and each bearing surface while flowing along the oil flow path 142.

However, when the oil flow path is formed in the rotation shaft 133 as illustrated in this embodiment, the rotation shaft 133 receives an axial load toward the second bearing 182 due to pressure of the oil storage portion having relatively high pressure.

Accordingly, the rotation shaft 133 may be pushed toward the suction space S1 by the pressure difference between the discharge space S2 and the suction space S1. At this time, when the rotation shaft 133 is supported by a ball bearing, the rotation shaft 133 may endure the axial load. However, when the rotation shaft 133 is supported by a bush bearing, the rotation shaft 133 may not endure the axial load, and thus an axial bearing has to be additionally provided.

FIG. 8 is a sectional view illustrating one example of an axial bearing in accordance with an embodiment of the present invention. As shown in the drawing, in this embodiment, a balance weight 135 may be used to form an axial bearing.

For example, in this embodiment, the balance weight 135 may be press-fitted into the second shaft portion 133 b of the rotation shaft 133. The balance weight 135 is positioned inside the first space portion 124 constituting the first back pressure space S3.

The axial supporting protrusion 126 may be formed at one end of the frame hole 125 constituting the first space portion 124 so as to form a first axial bearing surface corresponding to one side surface of the balance weight 135.

The axial supporting protrusion 126 is formed in an annular shape, and one end surface thereof, that is, a surface facing the second scroll 160 is ground to form an axial bearing surface 126 a. The axial bearing surface 126 a may be provided with a communication groove through which the back pressure space S3 and the suction space S1 communicate with each other.

Here, since the rotation shaft 133 is supported by the first scroll 150 and the casing 101 with the driving motor 103 interposed therebetween, the frame 102 is provided with a separate radial bearing. Therefore, since the second shaft portion 133 b of the rotation shaft 133 corresponding to the frame 102 does not need to be precisely ground, the balance weight 135 is press-fitted into the second shaft portion 133 b, and thereafter squareness processing is performed for only one side surface of the balance weight 135, namely, only a surface facing the axial supporting protrusion 126, thereby forming an axial bearing surface 135 a.

At this time, as the balance weight 135 is press-fitted into the second shaft portion 133 b so that one side surface thereof forms the axial bearing surface 135 a, it may be preferable to form an axial supporting surface 133 f on the second shaft portion 133 b to suppress the balance weight 135 from being pushed in an axial direction.

The axial supporting surface 133 f may be formed in a stepped manner so as to support another side surface of the balance weight 135, that is, another side surface of the balance weight 135 that faces the eccentric portion 133 c. Accordingly, the second shaft portion 133 b is formed to be stepped in two stages at the axial supporting surface 133 f. Accordingly, the weight balance 135 can be prevented from being pushed in the axial direction when the balance weight 135 applies a force to the axial bearing surface 133 f.

As described above, when one side surface of the balance weight 135 and the axial supporting protrusion 126 of the frame 102 corresponding to the one side surface form the axial bearing surface 133 f, an axial load can be attenuated by the axial bearing surfaces provided between the balance weight 135 and the frame 102 even if the rotation shaft 133 receives the axial load from the discharge space S2 to the suction space S1.

Accordingly, the rotation shaft 133 can be prevented from being pushed in the axial direction even while using the bush bearing as the first bearing 181 and the second bearing 182. This may prevent a leakage of refrigerant from the compression chamber in the axial direction, which is caused as the second scroll 160 coupled to the rotation shaft 133 is spaced apart from the first scroll 150, thereby improving efficiency of the compressor.

Hereinafter, description will be given of another embodiment of an axial supporting structure according to the present invention.

That is, in the foregoing embodiment, the rotation shaft is prevented from being pushed in the axial direction by using the balance weight and the frame corresponding to the balance weight. However, in this embodiment, a fluid bearing using oil as well as a mechanical bearing may be additionally provided between the balance weight and the frame. FIGS. 9 and 10 are sectional views illustrating different embodiments of an axial supporting structure according to the present invention.

As illustrated in FIG. 9, a fluid bearing according to this embodiment is configured to support the rotation shaft 133 in the axial direction by using pressure of oil that moves to another end of the rotation shaft 133 along the oil flow path 142. In this case, the rotation shaft 133 may be axially supported using only the fluid bearing. Alternatively, the rotation shaft 133 may be supported by using the fluid bearing together with the balance weight 135, not by using only the fluid bearing.

For example, the balance weight 135 is used as a first axial bearing and a second back pressure space S4 provided at the second end portion of the rotation shaft 133 is used as a second axial bearing, respectively. Since the first axial bearing has the same configuration as the aforementioned, and thus a description thereof will be omitted.

The second axial bearing is formed by the second back pressure space S4. The second back pressure space S4 may be defined as a space formed between a front end of the rotation shaft 133 and a second space portion 111 d provided on an inner circumferential surface of the second shaft supporting portion 111 c.

As described above, to form predetermined back pressure inside the second back pressure space S4, the oil flow path 142 of the rotation shaft 133 has to be formed through both ends of the rotation shaft 133. Accordingly, oil flowing into the oil flow path 142 of the rotation shaft 133 from the oil storage portion S22 is introduced and filled in the second back pressure space S4 due to a pressure difference.

At this time, in order to form the second back pressure space S4 as a sealed space, a third sealing member (not shown) may be provided between an outer circumferential surface of the second bearing portion 133 e and an inner circumferential surface of the second shaft supporting portion 111 c. The third sealing member may be provided on the rotation shaft 133 or the second shaft supporting portion 111 c at one side of the second bearing 182.

However, a separate third sealing member may not be provided when the second bearing 182 provided on the inner circumferential surface of the second shaft supporting portion 111 c is a bush bearing. In this case, the second back pressure space S4 may be sealed using a gap between the inner circumferential surface of the second bearing 182 and the outer circumferential surface of the second bearing portion 133 e. Then, the second back pressure space S4 may not be completely sealed but may ensure sealing strength high enough to form back pressure required by the second back pressure chamber S4.

When the second back pressure space S4 is formed between one end of the rotation shaft 133 and the casing 101 corresponding to the one end, oil flowing along the oil flow path 142 of the rotation shaft 133 is introduced into the second back pressure space S4, and the rotation shaft 133 is supported in a direction toward the discharge space by pressure of the introduced oil.

As a result, the rotation axis 133 can be suppressed from being pushed toward the suction space due to a pressure difference between the discharge space S2 and the suction space S1, thereby preventing the leakage from the compression chamber in the axial direction.

Then, as the second back pressure space S4 and the balance weight 135 both attenuate the axial load applied to the rotation shaft 133, so that the rotation shaft 133 can be supported more stably.

On the other hand, as illustrated in FIG. 10, the second bearing 182 may alternatively be a ball bearing. In this case, since an axial bearing force is generated by only the ball bearing, it is not necessary to form a separate second back pressure space.

Hereinafter, description will be given of another embodiment of a motor operated compressor according to the present invention.

That is, in the foregoing embodiment, the balance weight is accommodated in the first back pressure space. On the other hand, as illustrated in FIG. 11, the balance weight 135 may also be provided outside the first back pressure space S3. For example, the balance weight 135 may be coupled to the rotor 132 or to the rotation shaft 133.

Also, in this case, since a bearing surface for supporting the rotation shaft 133 is not formed on the frame 102, an axial length of the frame 102 can be reduced. Accordingly, a distance between the compression unit 105 and the driving motor 103 can be shortened, such that a part of the winding coil 131 a can overlap the balance weight 135 in the radial direction, and the length of the rotation shaft 133 can be shortened, which may result in reduction of an overall length of the compressor.

Although not shown, even in this embodiment, the second scroll may be a double-sided scroll. In this case as well, the basic configuration described above may be applied equally.

Hereinafter, description will be given of another embodiment of a first shaft supporting portion in a scroll compressor according to the present invention.

That is, in the foregoing embodiment, the first shaft supporting portion is formed on the first scroll. On the other hand, as shown in this embodiment, the first shaft supporting portion may alternatively be formed on the casing, namely, the rear housing. FIG. 12 is a sectional view illustrating another embodiment of a first shaft supporting portion according to the present invention.

As illustrated in FIG. 12, a scroll shaft hole 156 according to this embodiment may formed in the fixed disk portion 151 of the first scroll 150 so that the first bearing portion 133 d of the rotating shaft 133 is penetrated through. And, the first shaft supporting portion 112 c according to this embodiment may protrude from an inner surface of the rear housing 112 toward the fixed disk portion 151 of the first scroll 150 so that the first bearing portion is inserted and supported in the radial direction. The first shaft supporting portion 112 c may be formed in a cylindrical shape as shown in the foregoing embodiment, and a sealing member (not shown) may be provided between an end surface of the first shaft supporting portion 112 c and a rear surface of the corresponding fixed disk portion 151 to seal a gap between the discharge space S2 and the oil supply passage Fo.

As described above, when the first shaft portion 112 c is formed in the rear housing 112 other than the first scroll 150, it is easy to process the first scroll 150 which is relatively complicated and difficult to be processed. In addition, if the first shaft portion 112 c is used to press the first scroll 150 in a direction toward the second scroll 160, the axial leakage from the compression chamber V can be effectively fabricated. 

What is claimed is:
 1. A motor operated compressor, comprising: a driving motor having a rotation shaft; a frame provided on one side of the driving motor in an axial direction; an orbiting scroll supported on the frame in the axial direction and eccentrically coupled to the rotation shaft to perform an orbiting motion; a fixed scroll provided at an opposite side of the frame with the orbiting scroll interposed therebetween, the fixed scroll forming a compression chamber together with the orbiting scroll and supporting one end portion of the rotation shaft in a radial direction, wherein the rotation shaft passes through the frame and the orbiting scroll; and a casing provided at an opposite side of the frame with the driving motor interposed therebetween, the casing supporting another end portion of the rotation shaft in the radial direction.
 2. The compressor of claim 1, wherein the fixed scroll includes a first shaft supporting portion protruding therefrom, the one end portion of the rotation shaft being rotatably inserted in the first shaft supporting portion, and wherein the first shaft supporting portion includes a first bearing disposed on an inner circumferential surface of the first shaft supporting portion to support the one end portion of the rotation shaft.
 3. The compressor of claim 2, wherein the casing includes a second shaft supporting portion protruding therefrom in a direction toward the driving motor, the another end portion of the rotation shaft being rotatably inserted in the second shaft supporting portion, and wherein the second shaft supporting portion includes a second bearing disposed on an inner circumferential surface of the second shaft supporting portion to support the another end portion of the rotation shaft.
 4. The compressor of claim 3, wherein the frame includes a frame shaft hole through which the rotation shaft is inserted, and wherein a gap between an inner circumferential surface of the frame shaft hole and an outer circumferential surface of the rotation shaft is larger than one of a gap between an inner circumferential surface of the first bearing and the outer circumferential surface of the rotation shaft, or a gap between an inner circumferential surface of the second bearing and the outer circumferential surface of the rotation shaft.
 5. The compressor of claim 4, wherein the frame includes a first space portion formed on one side surface of the frame, the frame, the first space portion forming a first back pressure space together with the orbiting scroll, and wherein a sealing member for sealing the first back pressure space is provided between the inner circumferential surface of the frame shaft hole and the outer circumferential surface of the rotation shaft.
 6. The compressor of claim 1, wherein the fixed scroll includes a first bearing for supporting a first bearing portion of the rotation shaft, the casing includes a second bearing for supporting a second bearing portion of the rotation shaft, and the orbiting scroll includes a third bearing for supporting an eccentric portion of the rotation shaft, and wherein the first bearing includes one of a bush bearing or a needle bearing, the second bearing includes one of a bush bearing or a ball bearing, and the third bearing includes a bush bearing.
 7. The compressor of claim 1, wherein the rotation shaft includes a first bearing portion formed on the one end portion of the rotation shaft and supported by the fixed scroll, a second bearing portion formed on the another end portion of the rotation shaft and supported by the casing, and an eccentric portion formed between the first bearing portion and the second bearing portion, the eccentric portion configured to be eccentrically coupled through the orbiting scroll, and wherein a balance weight is coupled between the second bearing portion and the eccentric portion of the rotation shaft, and supported in the axial direction by being in contact with the frame.
 8. The compressor of claim 7, wherein the frame includes a first space portion formed on one side surface thereof, the first space portion forming a first back pressure space together with the orbiting scroll, and wherein the first space portion includes a bearing supporting protrusion protruding in the axial direction toward the balance weight, the bearing supporting protrusion forming a bearing surface with the balance weight in the axial direction.
 9. The compressor of claim 8, wherein the rotation shaft includes an axial supporting surface formed on an outer circumferential surface thereof in a stepped manner to support the balance weight in the axial direction.
 10. The compressor of claim 1, wherein the casing includes a second shaft supporting portion protruding therefrom in a direction toward the driving motor, the another end portion of the rotation shaft being rotatably inserted in the second shaft supporting portion, and wherein the second shaft supporting portion includes a second space portion spaced apart from an end portion of the rotation shaft, the second space portion configured to store a portion of oil discharged from the compression chamber.
 11. The compressor of claim 10, wherein the casing includes an oil storage portion configured to store oil which is discharged together with a refrigerant from the compression chamber and then separated from the refrigerant, and wherein the oil storage portion includes an oil supply passage formed between the oil storage portion and the another end portion of the rotation shaft, the oil supply passage being configured to guide the oil from the oil storage portion to a bearing surface.
 12. The compressor of claim 11, wherein the oil supply passage includes at least one pressure-reducing portion.
 13. The compressor of claim 1, wherein the casing includes a second shaft supporting portion protruding therefrom in a direction toward the driving motor, the another end portion of the rotation shaft being rotatably inserted in the second shaft supporting portion, and wherein at least a portion of the second shaft supporting portion axially overlaps a coil wound around the stator.
 14. The compressor of claim 1, wherein the frame includes a first space portion configured to form a first back pressure space together with the orbiting scroll, and wherein the first space portion axially overlaps at least part of a coil wound around the stator.
 15. The compressor of claim 1, wherein the rotation shaft includes a balance weight coupled to the rotation shaft, and wherein the balance weight axially overlaps at least part of a coil wound around the stator.
 16. A motor operated compressor, comprising: a driving motor having a rotation shaft; a frame having a frame shaft hole, the rotation shaft rotatably passing through the frame shaft hole; an orbiting scroll supported on the frame in an axial direction and having a rotation shaft coupling portion, the rotation shaft passing through the orbiting scroll and being eccentrically coupled to the orbiting scroll; a fixed scroll provided at an opposite side of the frame with the orbiting scroll interposed therebetween, the fixed scroll forming a compression chamber together with the orbiting scroll, the fixed scroll having a scroll shaft hole, the rotation shaft rotatably passing through the scroll shaft hole; a first shaft supporting portion provided on an inner surface of the casing forming a discharge space together with the fixed scroll, as the first shaft supporting portion being configure to support one end portion of the rotation shaft; and a second shaft supporting portion provided at an opposite side of the frame with the driving motor interposed therebetween, the second shaft supporting portion being configured to support another end portion of the rotation shaft.
 17. A motor operated compressor, comprising: a casing extending from adjacent a first side to adjacent a second side; a driving motor disposed in the casing; a frame disposed in the casing between the second side and the driving motor; a fixed scroll disposed in the casing between the second side and the frame; an orbiting scroll disposed in the casing between the fixed scroll and the frame, the fixed scroll and the orbiting scroll forming a compression chamber; and a rotation shaft supported by the casing adjacent the first side and by the fixed scroll adjacent the second side, the rotation shaft being eccentrically coupled to the driving motor.
 18. The motor operated compressor of claim 17, further including: a first shaft supporting portion protruding axially from the fixed scroll towards the second side; a first bearing disposed between the rotation shaft and an inner circumferential surface of the first shaft supporting portion; a second shaft supporting portion protruding from axially from the casing towards the second side; and a second bearing disposed between the rotation shaft and an inner circumferential surface of the second shaft supporting portion.
 19. The motor operated compressor of claim 18, further including: an oil supply passage extending from a first end of the rotation shaft disposed adjacent the first scroll towards a second end of the rotation shaft disposed adjacent the casing; and at least one oil supply hole in fluid communication with the oil supply passage, the at least one oil supply hole configured to supply oil from the oil supply passage to one of the first bearing or the second bearing.
 20. The motor operated compressor of claim 17, wherein the frame includes a frame shaft hole, and the rotation shaft is rotatably disposed within the frame shaft hole, the rotation shaft being separated from the frame by a circumferential gap. 